Process and device for the determination and regulation of the moisture content of lengths of material



Feb. 6,-1940: M. SIEGENHEIM 2,189,352.

OR THE PROCESS DEVICE F DETERMINATION AND REGULATION OF MOISTURE CONTENT 0 ENGTHS 0F MATERIAL Filed NOV. 1937 Patented Feb. 6, 1940 UNITED STATES PATENT OFFICE MINATION AND MOISTURE CONTENT TERIAL Max Siegenheim, Zittan REGULATION OF THE F GTHS 0F MA- Germany, assignor to the firm M. Rudolf Jahr, Ger-a, Germany Application November 9, 1937, Serial In Germany March 17, 1936 6 Claims.

The present invention relates to the determination of the moisture content of lengths of material, e. g. textile fabrics, by ascertaining their electrical conductivity.v Especially with these it is very important to ascertain the momentary degree of dryness, in order on the ,one hand to .be able to avoid an over-drying injurious to the quality, and on the other hand to cause the drying device to work up to the limits of its economy.

It is a known phenomenon that lengths of material, after giving ofi their moisture, become charged with static electricity, owing to the friction arising from their movement during the drying operation. There are also known devices which utilize-the value of this electricity for ascertaining the moisture content.' However, these devices operate in a faulty manner, because the strength of the electrostatic charge is dependent not only on the moisture content of the length of fabric, but primarily on the intensity of the friction arising. The intensity of the friction is dependent again on the speed with which the length of material runs'through the drying de- 95 v vice. A thick length of. material, which because of its greater moisture contentruns more slowly through the drying device, .hasby the consequentially reduced friction a smaller quantity of static electricity in it when the conditioning" moistness is attained, than a thin length of fabric, which because of its lower moisture content passes through the drying device with corre spondingly greater speed.

The invention relates to a process according to which, independently of the speedof movement of the length of material, by friction remaining always the same of an additional electricity generating means a value of static electricity is generated and measured which is influenced only by the moisture content of. the fabric. For this purpose there is employed according to the invention an additional electricity generating means which is driven separately and the speed of motion of which is variable and adapts itself in a suitable ratio proportion to the speed of the length of material. The ever uniform friction thereby attainable produces a. value of electricity which is-then dependent exclusively only upon the momentary moisture content of the length of material and can therefore be employed for measuring the same without objection.

An embodiment of. the invention is illustrated, by way of example, in the accompanying drawing in which Figs. 1 and 2 show in diagram form each one a different device for the application of the process according to the invention,

Fig. 3 illustrating the application of this process of regulation upon a device.

In Fig. 1 is A the drying device and B the issuing length of material. This is led over an electricity generating means, as which a driven roller C is shown which rubs on the length of material. The speed of movement of this electricity generating means is variable and is adapted by an additional controlmechanism D to the the receiving instrument E the momentary elec- I tricity value is according to Fig. 1 measured on the electricity generating means C. Or it is measured' on the length of fabric in the construction shown in Fig. 2 where the electricity connecting wire is laid not on the electricity generating means C but on a point of. the length of fabric located posterior the electricity generating means.

The quantity of electricity, which is produced by the friction during the travel of the length of material through the drying device, is led away at F by a sufiicient earth connection and cannot therefore influence the value of the electricity generated at C.

The construction and the arrangement of the electricity generating means are dependent on the construction of the drying device and on the character of the length of material.

The term dry is ascertained thereby that a measuring instrument is suitably calibrated for the electrostatic charge arising with dry goods at a definite intensity of. friction.

By a further development of the invention, a

regulation of the moisture content of the length of material issuing from the drying device can be attained. Thus for example upon increasing the intensity of friction of the electricity generating means upon the length of material, even with unchanged moisture content of the same, there results a greater electrostatic charge, which already causes the indication overdry in the easurirg instrument calibrated to normal by the additional moistness. In this case, the exciter circuit influenced through the measuring instrument as receiving device, regulates the drying device to greater speed, so that the length of. material then leaves the machine with greater moisture content. By a scale-divided provision for variation of the intensity of friction of the electricity generating means, there can in this way be produced a percentage regulation of the moisture content of the length of material to be dried.

Fig. 3 illustrates the application of this process of regulation upon adevice shown as an example of construction. The length of material B coming from the drying device A is in frictional contact with the electricity generating means C. The electricity generating means C depends for its speed of motion upon the speed of motion of the length of material in the inverse proportion. This regulation is effected by the control mechanism D. Accordingly the intensity of friction between length of material B and electricity generating means C remains always the same, even with a change of the speed of motion of the length of material. In order to vary the moistness of the length of material leaving the drying device, a stronger or weaker electrostatic charge must be produced by a greater or smaller-intensity of friction between electricity generating means and length of material. This is attained regulating gear G, through which the transmission ratio from the source of power H to the electricity generating means C can be adjusted by hand. This adjustment takes place according to a graduation which corresponds to the percentage of moistness of the length of material resulting as shown by experience from the variation of the intensity of friction. An adjustability of the percentage of moisture from 6 will be sufficient for this in most cases. The electrostatic charge,. stronger or weaker owing to the change of the driving speed, i. e. intensity of friction of the electricity generating means C, influences the measuring and receiving instrument E. The same, by a transmission current circuit, operates the auxiliary motor I, which varies the transmission ratio oi the source of power L actuating the driving device through the variable transmission gear K and thereby influences the speed of movement of the drying device A. The electrostatic charge obtained higher or lower by the movement of the length of material during drying is neutralized at F by earth-connection, in order to exclude erroneous results.

The construction and the arrangement of the regulating device for the moisture content of the lengths of material to be dried depends on the construction of the drying device as well as on the character of the length of material to be considered.

I claim:

1. A process for determiningthe moisture content of lengths of material by ascertaining their electrical conductivity consisting in conducting off the natural electricity from the length of material, producing a static electricity value influenced by the moisture content in said length of material and measuring this static electricity value to ascertain the conductivity and consequently the moisture content. I

2. A process for determining the moisture content of lengths of material by ascertaining their electrical conductivity, consisting in conducting off the natural electricity from the length of material, producing by friction by an additional generating means a static electricity value influenced by the moisture content in the material on said means and also on the length of material, measuring this static value to ascertain the electrical conductivity and consequently the moisture content, and maintaining constant said value irrespectively of the speed of the length of cloth.

3. A device for determining the moisture content of lengths of material by ascertaining their electrical conductivity as they run out of a drying device, comprising in combination an earth wire contacting with the material leaving the drying device, a driven roller bearing against the length of material to produce by friction a static electricity value dependent upon the moisture content in the cloth, means for picking up the generated electricity and a receiving device connected to said means and adapted to measure the static electricity value and thus determine the electrical conductivity and consequently the moisture content of the material.

4. A device as specified in claim 3 in which the driven roller is mounted in bearings insulated from earth.

5. A device as specified in claim 3 in which the driven roller is of non-conductive material.

6. In a device as specified in claim 3, means for driving said roller, and means controlled by the speed of the material for controlling the driving means of said roller.

MAX SIEGENHEM.

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